Investigation into the Effect of Mechanical Activation on the Leaching of Chalcopyrite in a Glycine Medium

چکیده مقاله

The effect of mechanical activation on the leaching and electrochemistry of chalcopyrite was investigated in a glycine medium. Leaching experiments were conducted to evaluate the effect of particle size (with re-ground sample in ball mill) and mechanical activation (with re-ground sample in planetary mill for 4 h) on chalcopyrite dissolution in a stirred tank reactor. Results show that a maximum copper extraction (95.1%) was obtained for mechanically activated chalcopyrite after 12 h leaching in a 0.4 M glycine solution at 60 ◦C, 2% (w/v) pulp density and an initial solution pH of 10.5. Under these same leaching conditions, a decrease in particle size for conventionally ground chalcopyrite from 106 to 125 μm to <20 μm, led to a substantial increase in the level of copper extraction - from 0.6% to 33.8%. Analysis of solid residue by XRD showed that iron could be precipitated as maghemite and a part of dissolved copper could be removed from the solution as copper glycinate crystals and covellite. Result of the electrochemical analysis showed that the anodic current of the chalcopyrite‑carbon paste electrode was significantly increased for the mechanically activated sample. Nevertheless, anodic current densities were observed to reduce during subsequent voltammetry cycles as a consequence of passivating the surface of chalcopyrite electrode by reaction products and decreasing electroactive cites the electrode surface. A new 2- stage leaching flowsheet was proposed to extract copper from chalcopyrite concentrates in glycine media. Glycine leaching with mechanical activated pretreatment could be a promising method for treating low-grade chalcopyrite concentrates.